1. Field of the Invention
The present invention relates to a disc drive suspension incorporated in an information processor, such as a personal computer.
2. Description of the Related Art
A hard disc drive (HDD) that is used to record in or retrieve information from a rotating magnetic disc or magneto-optical disc has a carriage that can turn around a shaft. The carriage is turned around the shaft by means of a positioning motor. The carriage comprises an actuator arm, a suspension provided on the distal end portion of the arm, a head section including a slider mounted on the suspension, etc.
When the disc rotates, the slider on the distal end portion of the suspension slightly lifts above the surface of the disc, and an air bearing is formed between the disc and the slider. The suspension comprises a baseplate, load beam, flexure, wiring member, etc.
A conventional disc drive suspension 1 shown in FIG. 11, for example, has a hinge portion 4 that can bend in its thickness direction between a load beam 2 and a baseplate 3. A wiring member 5 is located outside the hinge portion 4 so as to extend along it. The load beam 2 has a proximal portion 2a, on which the baseplate 3 is placed, and a beam body 2b that extends from the hinge portion 4 toward a head section 6. A wiring supporting portion 7 is formed on the proximal portion 2a of the load beam 2.
FIG. 12 shows the oscillation characteristic of the head section 6 of the suspension 1 in the track direction (indicated by arrow Y in FIG. 11). An oscillation B1 in a primary bending mode appears near the frequency point of 3 kHz. An oscillation T1 in a primary twist mode appears near 9 kHz. Further, an oscillation Sway in a sway mode appears near 16 kHz.
In the suspension 1 having the wiring member 5 that passes outside the hinge portion 4, as in the prior art example described above, the configuration near the hinge portion 4 is asymmetric. Thus, a relatively great oscillation B1 in the primary bending mode appears in the low-frequency band. In an actual disc drive, the oscillation in the low-frequency band is easily amplified by a servomechanism that drives the suspension 1, thus arousing the problem of off-track operation.
In a conventional suspension 1′ shown in FIG. 13, on the other hand, a wiring member 5 passes inside a hinge portion 4. The wiring member 5 is fixed to a wiring supporting portion 8 that protrudes sideways from a baseplate 3. That part of the suspension 1′ which is situated near the hinge portion 4 is bisymmetrical.
FIG. 14 shows the oscillation characteristic of the suspension 1′ in the track direction. Since that part of the suspension 1′ near the hinge portion 4 is bisymmetrical, the oscillation B1 in the primary bending mode is improved considerably. However, the oscillation B1 in the primary bending mode slightly appears in the low-frequency band of 3 to 4 kHz. Thus, there is room for improvement with respect to the problem of off-track operation.
Full line M1 in FIG. 15 represents the swing of the wiring supporting portion 8 of the suspension 1′ in the thickness direction (indicated by arrow Z in FIG. 13). Broken line M2 in FIG. 15 represents the swing of the distal end portion of a load beam 2 in the thickness direction. In this prior art example, the wiring supporting portion 8 having a relatively great mass laterally projects long from the suspension 1′. As the wiring supporting portion 8 of this example swings in the Z-direction, therefore, torsion is induced, so that the track-direction swing is enhanced in the low-frequency band.